this word originated from the short-form of a certain, Singaporean named weisheng. apparently the "eng" in weisheng is exceptionally hard to pronounce, so his friends started to call him "weish", which is pronounce as "waysh". Weisheng is in a very fit condition, with a body to die for. Weish is defined as a state in which an individual is very manly and of immense masculinity. (VERB, NOUN, ADVERB, ADJECTIVE)

SIALA. YOU DAMN WEISH LEH!
DAMN I NEED TO BE WEISH.
HERE COMES A WEISH.
I'M DETERMINED TO BECOME WEISH-ED.